Diazotype copying apparatus



Aug. 20, 1968 J. L. PRATT, JR

DIAZOTYPE COPYING APPARATUS 2 Sheets-Sheet 1 Filed June 15, 1965 s o I FIG.I

FIG.2

INVENTOR. JAMES L. PRATT JR.

W4: 2AM

ATTORNEY Aug. 20,1968 J. L. PRATT, JR

l DIAZOTYPE COPY ING APPARATUS Filed June 15, 1965 2 Sheets- Sheet 2 FIG mmvrm JAMES L. PRATT JR.

M g/CM ATTORNEY United States Patent 3,397,630 DIAZOTYPE COPYING APPARATUS James L. Pratt, In, Saugerties, N.Y., assignor to GAF Corporation, a corporation of Delaware Filed June 15, 1965, Ser. No. 464,101 6 Claims. ((31. 95-75) ABSTRACT OF THE DISCLOSURE A single radiation source having a wide spectral energy range is used to supply both ultraviolet and infrared radiation. The apparatus permits the separation of the ultraviolet and infrared light, so as to direct each to a separate sheet support area. A conveyor belt passes the sensitized material and the original in conjunction past the supports. A dichroic reflector and a dichroic filter are used in conjunction for directing the ultraviolet and infrared radiation along different paths.

This invention relates to photocopying apparatus and, more particularly, to apparatus utilizing diazo-sensitized copy materials.

Diazotype printing and developing machines are widely used in duplicating drawings or other translucent graphic originals and have the advantage of providing a direct positive copy which can be used without further processing or drying. Such machines generally utilize a translucent printing cylinder containing a high-intensity mercury vapor lamp. The original, in contact with the diazo-sensitized sheet material, is conveyed around the cylinder for the purpose of exposure to the radiation of the mercury vapor lamp.

It is to be noted that diazo-sensitized mtterials are actinically sensitive to spectral energy in the ultraviolet range, hereinafter referred to as U.V. For this reason, mercury vapor lamps are used inasmuch as they contain, in their radiation range, approximately 30% U.V., 20% visible, and 50% infrared. Only marginal portions of the visible and none of the infrared radiation is of any use in the exposure of diazotype material. However, these radiations accompany the useful U.V. portion and represent a waste of considerable energy, manifesting itself in the production of heat which must be dissipated. For this reason, elaborate cooling systems are generally provided in conventional diazo reproduction apparatus, particularly for cooling of the printing cylinder which houses the source of radiation, namely, 'the mercury vapor lamp.

It is, accordingly, the primary object of this invention to increase the efficiency of the exposure apparatus utilizing a source of U.V. radiation, such as a mercury vapor lamp.

Another object of the invention is to utilize both the ultraviolet and the infrared spectra of the radiation for the processing of such diazotype materials which are heat reactive in that the latent image may be developed by the application of heat without the use of conventional aqueous ammonia for development.

In the attainment of the objects, means are provided for filtering and directing the useful radiation of the spectral energy of such lamps to irradiate the sensitized material and, correspondingly, means are provided for preventing the unwanted radiation from reaching the material.

Other objects and features will be apparent from the following description of the invention, pointed out in particularity in the appended claims and taken in connection with the accompanying drawings in which:

FIG. 1 is a schematic representation in cross section of one form of a copying apparatus incorporating the features [of this invention;

lot:

FIG. 2 is a schematic representation in cross section of a modified form of the apparatus;

FIG. 3 is a schematic representation in cross section of another modification of the apparatus utilizing a rotating printing cylinder; and

FIG. 4 is a schematic representation in cross section of a further modification of the apparatus.

Referring to the figures, the apparatus shown in FIG. 1 comprises a housing 5 of generally oblong shape having a front wall 6 and a bottom wall 7. Both of these walls are slightly curved and made of glass of which front wall 6 possesses the property of freely passing radiation in the untraviolet spectrum. High silica or lime soda glass is eminently satisfactory for this purpose.

The walls 6 and 7 function as platens over which the diazotype material is conveyed for exposure to radiation. For this purpose a conveyor belt 8 running over rollers 9 and 10 is arranged in contact with the outer surface of the platen 6. Another belt 11 running over rollers 12 and 13 is arranged to contact the outer surface of the platen 7. A motor 15 is shown, by way of example, as the motive means for driving the rollers 9 and 13 by means of a drive belt 16.

Near the roller 12 is a feedboard 18 over which the original and the copy material is placed in superposed relation for transport into, or exit from, the apparatus, depending upon the direction of rotation of the motor 15. As will be seen later, the direction of feed is selected in accordance with the type of copy desired from the material to be handled. The top portion of the apparatus has also a feedboard 19 placed over a layer 20 of heat insulating material. A deflector plate 21 guides the copy material onto the board 19. A separation device 22 between the rollers 9 and 13 functions, in one direction of operation, to separate the original from the sensitized material and to direct it into a receiving tray 24. The function of the above-described components will be more fully explained in connection with the description of the operation of the copying apparatus.

In the casing 5 is placed a tubular mercury vapor lamp 25 which is the light source and from which emanates radiations in the ultraviolet and infrared spectra in the ratio as previously mentioned. The light source 25 is in the focal point of a parabolic reflector 26 so that the radiation utilized for exposure is directed toward the platen 6. Between the light source 25 and the platen 6 is placed a filter plate 27 which has a particular characteristic in that it will freely permit radiation in the ultraviolet spectrum to reach the platen 6- but will prevent radiation in the infrared spectrum to pass in the same direction. The construction of the filter plate 27 is of special significance in the operation of the exposure unit. Both the plate 27, as well as the exposure platen 6, are made of glass of the type which transmits ultraviolet radiation, as for example, high silica or lime soda glass. However, the filter plate 27 has a particular coating which permits the free passage of U.V. radiation, but reflects the infrared portion of the spectrum. Such a coating is known as a multilayer optical interference coating and is applied by vacuum deposition methods. It consists of alternate layers of materials of high and low refractive index having a thickness of about one-quarter of the wave length of light. These are commercially available in various properties of spectral reflectivity and transmissivity. For example, the filter plate 27, having the above desired properties, may have the Bausch & Lomb coating -359 or the Fish-Schurman coating 6143.

The reflector 26, on the other hand, is made of glass with a special multilayer interference coating on one or both sides thereof which strongly reflects U.V. radiation, but allows the free passage of the unwanted portion, particularly the infrared rays. Such a coating is commercially available under the trade name Fish-Schurman Filter 3025" or Tiffen Filter 83. In fact, both the reflector 26 and the filter plate 27 perform the function of dichroic filters to separate the useful radiation and direct it to the sensitized material for exposure and to reflect the unwanted portion of the spectrum, particularly the infrared rays, and direct these to platen 7 for use in the heat development or heat printing of the exposed material.

From the above description, it is seen that, as to basic elements, the copying apparatus consists of a light source and two distinct supports irradiated from this source with selected spectra of the radiated energy. Each surface has conveying means for passing the sensitized material over it, either for exposure or for development. These basic elements of the apparatus are found in diverse form in the various modifications shown in FIGS. 2, 3 and 4. The construction in FIG. 2 is very much the same as in FIG. 1, except that the filter plate 27 is tilted, thereby eliminating the dichroic properties needed for the reflector 26 and also the heat reflector 28. The parabolic reflector 26 is placed against the side 31 of the housing and in the focal point thereof is the light source 28. The U.V. radiation will pass freely through the filter plate 27 impinging on the platen 6, whereas the infrared portion of the emitted radiation is prevented from passing. It is reflected from the filter plate 27 and directed, by virtue of its angular placement, onto the platen 7. The conveyor belts and motor means are the same as in FIG. 1 and need not be described in detail.

The apparatus shown in FIG. 3 departs from the previous ones in that in place of platens, the distinct supports are portions of a conventional transparent printing cylinder 32 which is rotatably mounted in suitable bearings, not shown here. The cylinder 32 is driven by endless belt 33 which runs over strategically placed rollers 34, 35, 36, and 37. Drive may be effected by coupling of a motor to any one of the rollers.

Within the printing cylinder 32, near the upper half thereof, is placed a parabolic reflector 26 in the focal point of which is the light source 25. Facing the reflector, and tilted at an angle, is the filter plate 27. Feedboard 18 is arranged at the lower end of the cylinder 32 for operation in one direction of rotation and a feedboard 19 at the top side for operation in the other direction of rotation. By virtue of the properties of the filter plate 27, it becomes apparent that the radiation from the source 25, in cooperation with the reflector 26, is directed onto the plate 27 and will irradiate the portion A-B of the cylinder 32 with U.V. energy. On the other hand, the infrared spectra is diverted by virtue of the reflection from the plate 27 toward the portion C-D of the cylinder 32.

The apparatus shown in FIG. 4 represents another form utilizing the essential elements of the invention. The curved platens 6 and 7 form a unitary structure being fused together by the beads 40 and 41 which also hold the filter plate 27. The latter acts as a dividing wall between the two above-mentioned elements. The right-hand side portion houses the light source 25. A conveyor belt 11 placed over rollers 12, 13 and 14 contacts the outer surface of the platen 7. Another conveyor belt 8 placed over rollers 9 and 10 contacts the outer surface of the platen 6. A curved feedboard 42 serves for the entrance of the copy material, consisting of the original to be copied, indicated as O, and the sensitized material, indicated as S. These are placed in superposed relation. Another feedboard 43 serves for the entry of the material between the conveyor belt 11 and the roller 14. A tray 44- in conjunction with deflector plate 45 serves for the guiding and depositing of the copies, respectively.

In discussing the operation of the various forms of the apparatus, let us emphasize the fact that the diazo material to be used in conjunction with these is of the type generally known as thermodiazo material. These materials require no chemical treatment for development of the latent image but only the application of heat. They are sensitive to U.V. radiation as are conventional diazo materials and, if exposed through a transparent original, will form a positive image which will become visible upon application of heat. Conversely, if such a material is first exposed to heat radiation, e.g., by reflection from a copy material which may be opaque, a reflex image is obtained which, upon further exposure to U.V. radiation will become visible. In this manner, it is feasible to make copies from an opaque original in a manner similar to those which can be obtained with heat reactive copy materials. This is generally known as thermoprinting. The apparatus herein shown in various forms may therefore be used for conventional diazo reproduction or, if de sired, for reflex copying.

Referring to the operation and considering FIG. 1, let us assume that we intend to have copies only from a transparent original. For this purpose, platen 6 is first utilized. The motor 15 is placed into operation to run in such direction as to move the conveyor belt 8 downwardly over the platen 6. The transparent original 0 is placed under the sensitized sheet S and both are fed over the board 19 and, guided by deflector plate 21, will pass by the belt 8 over the platen 6. In passing, it is exposed with radiation in the U.V. portion of the spectrum since, as mentioned before, the filter plate 27 allows U.V. to pass but reflects the infrared rays. Thereafter, the material is passed between the belt 11 and the platen 7. Here it is subjected to a strong infrared radiation by virtue of the energy concentrated there from the reflector 28 and from heating elements 29 and 30 and thus heat development takes place. The material emerges over the feedboard 18.

When reflex copies are to be made, the direction of the motor 15 is reversed and the material is placed over the feedboard 18 in such relation that the original 0 is on top and the sensitized material S is on the bottom. As it passes under the platen 7, it is subjected to infrared radiation, resulting in an imagewise exposure since the heat absorbed by the dark areas, such as the letters of a printed page, will be more intense than that in the white areas. After heat exposure, the material leaves the apparatus by virtue of the deflector plates 22 and falls into the receiving tray 24. The sensitized sheet is then separated from the original and is fed into the U.V. portion of the apparatus for development, eg the burning off of the diazo compound in the non-coupled areas.

The operation of the apparatus, as to the other figures, is essentially the same as above described. In the construction shown in FIG. 2, the procedure is exactly the same as that in FIG. 1 since the constructional improvement of the tilting of the filter plate 27 does not in any way affect the modus operandi. It may be mentioned, however, that in this construction, auxiliary heater element 29 and as need not be employed.

The construction shown in FIG. 3 utilizes a rotating glass cylinder 32 which allows either U.V. or infrared radiation to pass through. When a copy is to be made of a transparent original, the latter, indicated as 0, is placed over the sensitized sheet, indicated as S, and allowed to enter over the board 18 between the bite of the belt 33 and the roller 37. This portion of the cylinder 32 is irradiated with U.V. from the light source 25 due to the filtering action of the plate 27 whereas the infrared portion of the spectrum from the lamp 25 is reflected from this plate toward the rear of the revolving cylinder. Consequently, while the material passes portion A-B it will be exposed from a latent image and as it passes over the portion C-D it will be heated for development of the image. The original is then separated from the sensitized sheet by the separator 22, being delivered rearW-ardly of the apparatus whereas the copy follows the cylinder and is deposited on the feedboard 19.

In the reverse operation for making reflex copies, the cylinder is caused to turn in a counterclockwise direction so that the material is fed in from the feedboard 19, entering first the infrared irradiated potion D-C and, thereafiter, the U.V. portion B-A to be deposited on the feedboard 18. It is to be noted that in reflex copying the original 0 is placed under the sensitized material S so that the latter faces the printing cylinder and the radiation.

The apparatus in FIG. 4 is compact in the sense that both platens '6 and 7, as well as the filter plate 27, are of unitary construction forming a solid assembly. In making copies from a transparent original, the material is fed over the feedboard 42 to enter over the roller between the belt 8 and the platen 6. The rollers 9 and 10 run in a counterclockwise direction passing the material over the surface of the platen 6 to be exposed to U.V. radiation from the source 25 through the filter plate 27. The original is then diverted by the separator 22 and guided by the deflector plate 45 and falls into the reeciving tray 44. The copy sheet continues in the direction toward the bite of the belt 11 at roller 12 to be passed over the platen 7 for heat development.

If a reflex copy is desired to be made, the material is inserted into the apparatus over the feedboard 43 so that it will pass first over the platen 7 for infrared irradiation and then over the platen 6 for U.V. exposure. The order of placement of the material is reversed in that the original is placed on top and the sensitized material on the bottom thereof prior to insertion into the apparatus over the board 43.

What is claimed is:

1. In a duplicating apparatus utilizing heat-reactive diazo-sensitized material which, in contact with an original, as a two-ply assembly, are processed for producing copies, a single radiation source having a wide range of spectral energy including the ultraviolet and infrared, a first support, means for selecting a desired spectral range of radiation including the ultraviolet from said source, means for irradiating said support with said selected spectral radiation from said source, a second support, means for selecting another spectral range including the infrared from said source, means for irradiating said second support with said other selected spectral range of energy from said source, conveyor means for passing said two-ply assembly past said supports in sequence, and means for sequential irradiation with said selected spectral ranges, one of said selected spectral ranges effecting exposure of said sensitized material and the other of said selected spectral ranges effecting the development thereof.

2. Apparatus in accordance with claim 1 wherein said conveying means are reversible for passing said two-ply assembly in the opposite direction for radiation first by said second spectral energy, and thereafter by said first spectral energy for producing reflex copies from an opaque original.

3. A thermodiazo processing apparatus comprising a substantially rectangular housing having a first horizontally-disposed platen of vitreous material, an endless conveyor belt in contact therewith, a second vertically-disposed platen and an endless conveyor belt in contact therewith, rollers for moving said belts and motor means for driving said rollers selectively in either one direction or the other, a single mercury vapor lamp in said housing, a dichroic reflector for concentrating energy of the U.V. range of said lamp onto said vertical platen, a dichroic filter plate for reflecting the infrared component of the radiated energy from said source and simultaneously passing the ultraviolet component thereof for exposure of the diazo-sensitized material passing over said vertical platen.

4. A thermodiazo processing apparatus comprising a substantiallyrectangular housing having a first horizontallydisposed platen of vitreous material, an endless conveyor belt in contact therewith, a second vertically-disposed platen and an endless conveyor belt in contact therewith, rollers for moving said belts and motor means for driving said rollers selectively in either one direction or the other, a mercury vapor lamp in said housing, a dichoric reflector for concentrating energy of the U.V. range of said lamp onto said vertical platen, a dichoric filter plate for reflecting the infrared component of the radiated energy from said source and simultaneously passing the ultraviolet component thereof for exposure of the diazo-sensitized material passing over said vertical platen, a second reflector within said casing having the property of reflecting the infrared component of said energy source, said second reflector being disposed to direct the infrared energy onto said horizontal platen for infrared exposure of said sensitized material.

5. Apparatus in accordance with claim 1 wherein said supports are contiguous, representing portions of a rotating cylinder of vitreous material.

6. Apparatus in accordance with claim 1 wherein said means for selecting a spectral range comprises a dichoric filter plate.

References Cited UNITED STATES PATENTS 3,202,070 8/ 1965 Pratt et a1 -75 XR 3,307,465 3/1967 Adair 9575 XR 3,318,219 5/ 1967 Anderson 95-73 NORTON ANSHER, Primary Examiner.

G. M. HOFFMAN, Assistant Examiner. 

